#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
void main()
{
	int i,j;
	int x=0;
	int y=5;
	int velocity_x=1;
	int velocity_y=1;
	int left=0;
	int right=20;
	int top=0;
	int bottom=10;
	
	while(1)
	{
		x=x+velocity_x;
y=y+velocity_y;
		system("cls");
	for(i=0;i<x;i++)
		printf("\n");
	for(j=0;j<y;j++)
		printf(" ");
	printf("O\n");
	Sleep(50);
	if ((x==top)||(x==bottom))
velocity_x=-velocity_x;
if ((y==left)||(y==right))
velocity_y=-velocity_y;

}
}